Ashley is 2 times as old as Brandon. Nine years ago, Ashley was 5 times as old as Brandon. How old is Brandon now?
Explanation: We can use the given information to write down two equations that describe the ages of Ashley and Brandon. Let Ashley's current age be $a$ and Brandon's current age be $b$ The information in the first sentence can be expressed in the following equation: $a = 2b$ Nine years ago, Ashley was $a - 9$ years old, and Brandon was $b - 9$ years old. The information in the second sentence can be expressed in the following equation: $a - 9 = 5(b - 9)$ Now we have two independent equations, and we can solve for our two unknowns. Because we are looking for $b$ , it might be easiest to use our first equation for $a$ and substitute it into our second equation. Our first equation is: $a = 2b$ . Substituting this into our second equation, we get: $2b$ $-$ $9 = 5(b - 9)$ which combines the information about $b$ from both of our original equations. Simplifying the right side of this equation, we get: $2 b - 9 = 5 b - 45$ Solving for $b$ , we get: $3 b = 36.$ $b = 12$.